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Plasma end-loss studies on Scylla I-C

Technical Report ·
DOI:https://doi.org/10.2172/7258515· OSTI ID:7258515
The end-loss process in the collision dominated Scylla I-C plasma has been investigated with a local pressure sensitive diagnostic, integrated density measurement and axially arrayed diamagnetic loop probes. The development of a plasma loss orifice, well within the theta-pinch coil, has been identified. The magnitude of the observed orifice is found to be in excellent agreement with that predicted from collisional MHD theories. The axially flowing plasma is well confined until it flows through the loss orifice. After passing through the orifice, rapid axial expansion is observed. An indication of the existence of inward traveling rarefaction waves has been observed from the plasma midplane temperature data; an abrupt decrease in the plasma temperature at t approximately equal to 6.5 ..mu..s corresponds to the predicted time of arrival of rarefaction waves at the coil midplane. The plasma loss rate derived from the pressure data indicates an initial period (t < 4 ..mu..s) of rapid particle loss followed by a period (t > 4 ..mu..s) of gradual decay in the loss rate. This initial period of high loss rate is predicted from the MHD flow theories when the measured, time dependent plasma parameters are substituted into the analytical models. The loss rate determined from the end-on interferograms does not respond to the detailed structure of the plasma loss process.
Research Organization:
Los Alamos Scientific Lab., N.Mex. (USA)
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
7258515
Report Number(s):
LA-6412-MS
Country of Publication:
United States
Language:
English